[Renate]

You're quite right, there is more to it than just the loan that I quoted.

<loanToken>
  <time>...</time>
  <user>...</user>
  <operatorURL>...</operatorURL>
  <licenseURL>...</licenseURL>
  <loan>...</loan>
  <signature>...</signature>
</loanToken>

There's also the manifest.xml file which keeps track of what page you're on.

Then under "C:\Users\Whoever\Documents\My Digital Editions" is a bunch of stuff.
For me, I see a Gigabyte of expired library books.

Well, I cleaned up a bunch of stuff. Then I copied over the book that I really wanted and activation.xml did not change at all. I then copied over "Curious George and the Pizza Party", a PDF (which got bad reviews) and it updated.